src/go/collectors/go.d.plugin/modules/cassandra/integrations/cassandra.md
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# Cassandra
<img src="https://netdata.cloud/img/cassandra.svg" width="150"/>
Plugin: go.d.plugin
Module: cassandra
<img src="https://img.shields.io/badge/maintained%20by-Netdata-%2300ab44" />
## Overview
This collector gathers metrics about client requests, cache hits, and many more, while also providing metrics per each thread pool.
The [JMX Exporter](https://github.com/prometheus/jmx_exporter) is used to fetch metrics from a Cassandra instance and make them available at an endpoint like `http://127.0.0.1:7072/metrics`.
This collector is supported on all platforms.
This collector supports collecting metrics from multiple instances of this integration, including remote instances.
### Default Behavior
#### Auto-Detection
This collector discovers instances running on the local host that provide metrics on port 7072.
On startup, it tries to collect metrics from:
- http://127.0.0.1:7072/metrics
#### Limits
The default configuration for this integration does not impose any limits on data collection.
#### Performance Impact
The default configuration for this integration is not expected to impose a significant performance impact on the system.
## Metrics
Metrics grouped by *scope*.
The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.
### Per Cassandra instance
These metrics refer to the entire monitored application.
This scope has no labels.
Metrics:
| Metric | Dimensions | Unit |
|:------|:----------|:----|
| cassandra.client_requests_rate | read, write | requests/s |
| cassandra.client_request_read_latency_histogram | p50, p75, p95, p98, p99, p999 | seconds |
| cassandra.client_request_write_latency_histogram | p50, p75, p95, p98, p99, p999 | seconds |
| cassandra.client_requests_latency | read, write | seconds |
| cassandra.row_cache_hit_ratio | hit_ratio | percentage |
| cassandra.row_cache_hit_rate | hits, misses | events/s |
| cassandra.row_cache_utilization | used | percentage |
| cassandra.row_cache_size | size | bytes |
| cassandra.key_cache_hit_ratio | hit_ratio | percentage |
| cassandra.key_cache_hit_rate | hits, misses | events/s |
| cassandra.key_cache_utilization | used | percentage |
| cassandra.key_cache_size | size | bytes |
| cassandra.storage_live_disk_space_used | used | bytes |
| cassandra.compaction_completed_tasks_rate | completed | tasks/s |
| cassandra.compaction_pending_tasks_count | pending | tasks |
| cassandra.compaction_compacted_rate | compacted | bytes/s |
| cassandra.jvm_memory_used | heap, nonheap | bytes |
| cassandra.jvm_gc_rate | parnew, cms | gc/s |
| cassandra.jvm_gc_time | parnew, cms | seconds |
| cassandra.dropped_messages_rate | dropped | messages/s |
| cassandra.client_requests_timeouts_rate | read, write | timeout/s |
| cassandra.client_requests_unavailables_rate | read, write | exceptions/s |
| cassandra.client_requests_failures_rate | read, write | failures/s |
| cassandra.storage_exceptions_rate | storage | exceptions/s |
### Per thread pool
Metrics related to Cassandra's thread pools. Each thread pool provides its own set of the following metrics.
Labels:
| Label | Description |
|:-----------|:----------------|
| thread_pool | thread pool name |
Metrics:
| Metric | Dimensions | Unit |
|:------|:----------|:----|
| cassandra.thread_pool_active_tasks_count | active | tasks |
| cassandra.thread_pool_pending_tasks_count | pending | tasks |
| cassandra.thread_pool_blocked_tasks_count | blocked | tasks |
| cassandra.thread_pool_blocked_tasks_rate | blocked | tasks/s |
## Alerts
There are no alerts configured by default for this integration.
## Setup
### Prerequisites
#### Configure Cassandra with Prometheus JMX Exporter
To configure Cassandra with the [JMX Exporter](https://github.com/prometheus/jmx_exporter):
> **Note**: paths can differ depends on your setup.
- Download latest [jmx_exporter](https://repo1.maven.org/maven2/io/prometheus/jmx/jmx_prometheus_javaagent/) jar file
and install it in a directory where Cassandra can access it.
- Add
the [jmx_exporter.yaml](https://raw.githubusercontent.com/netdata/go.d.plugin/master/modules/cassandra/jmx_exporter.yaml)
file to `/etc/cassandra`.
- Add the following line to `/etc/cassandra/cassandra-env.sh`
```
JVM_OPTS="$JVM_OPTS $JVM_EXTRA_OPTS -javaagent:/opt/jmx_exporter/jmx_exporter.jar=7072:/etc/cassandra/jmx_exporter.yaml
```
- Restart cassandra service.
### Configuration
#### File
The configuration file name for this integration is `go.d/cassandra.conf`.
You can edit the configuration file using the `edit-config` script from the
Netdata [config directory](/docs/netdata-agent/configuration/README.md#the-netdata-config-directory).
```bash
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/cassandra.conf
```
#### Options
The following options can be defined globally: update_every, autodetection_retry.
<details><summary>Config options</summary>
| Name | Description | Default | Required |
|:----|:-----------|:-------|:--------:|
| update_every | Data collection frequency. | 5 | no |
| autodetection_retry | Recheck interval in seconds. Zero means no recheck will be scheduled. | 0 | no |
| url | Server URL. | http://127.0.0.1:7072/metrics | yes |
| username | Username for basic HTTP authentication. | | no |
| password | Password for basic HTTP authentication. | | no |
| proxy_url | Proxy URL. | | no |
| proxy_username | Username for proxy basic HTTP authentication. | | no |
| proxy_password | Password for proxy basic HTTP authentication. | | no |
| timeout | HTTP request timeout. | 2 | no |
| not_follow_redirects | Redirect handling policy. Controls whether the client follows redirects. | no | no |
| tls_skip_verify | Server certificate chain and hostname validation policy. Controls whether the client performs this check. | no | no |
| tls_ca | Certification authority that the client uses when verifying the server's certificates. | | no |
| tls_cert | Client TLS certificate. | | no |
| tls_key | Client TLS key. | | no |
</details>
#### Examples
##### Basic
A basic example configuration.
```yaml
jobs:
- name: local
url: http://127.0.0.1:7072/metrics
```
##### HTTP authentication
Local server with basic HTTP authentication.
<details><summary>Config</summary>
```yaml
jobs:
- name: local
url: http://127.0.0.1:7072/metrics
username: foo
password: bar
```
</details>
##### HTTPS with self-signed certificate
Local server with enabled HTTPS and self-signed certificate.
<details><summary>Config</summary>
```yaml
jobs:
- name: local
url: https://127.0.0.1:7072/metrics
tls_skip_verify: yes
```
</details>
##### Multi-instance
> **Note**: When you define multiple jobs, their names must be unique.
Collecting metrics from local and remote instances.
<details><summary>Config</summary>
```yaml
jobs:
- name: local
url: http://127.0.0.1:7072/metrics
- name: remote
url: http://192.0.2.1:7072/metrics
```
</details>
## Troubleshooting
### Debug Mode
To troubleshoot issues with the `cassandra` collector, run the `go.d.plugin` with the debug option enabled. The output
should give you clues as to why the collector isn't working.
- Navigate to the `plugins.d` directory, usually at `/usr/libexec/netdata/plugins.d/`. If that's not the case on
your system, open `netdata.conf` and look for the `plugins` setting under `[directories]`.
```bash
cd /usr/libexec/netdata/plugins.d/
```
- Switch to the `netdata` user.
```bash
sudo -u netdata -s
```
- Run the `go.d.plugin` to debug the collector:
```bash
./go.d.plugin -d -m cassandra
```